Note: Descriptions are shown in the official language in which they were submitted.
2194422
-2- 29058
This invention relates generally to breaking a web along
spaced lines of weakness. More specifically, the invention
includes methods and apparatus for breaking continuous webs, such
as plastic webs, in making plastic bags or groups of plastic bags,
or other workpieces, and shingling or otherwise accumulating the
workpieces.
BA K tR0 OF TH . INVE~rnu
This invention comprises novel apparatus and methods for
breaking a web along spaced lines of weakness. Apparatus for
breaking a web are known in the art. Gietman et al, U.S. Patent
5,362,013 discloses apparatus that breaks a plastic web along
spaced perforation lines. The Gietman et al device feeds the web
through a haul-in assembly 202 to a tumbler assembly 203. The
tumbler assembly 203 comprises a tumbler 225 and stationary guide
rolls 217-222. As shown in FIGURE 3 of Gietman et al, tumbler 225
rotates in a counterclockwise direction such that spools 226 and
227 stretch, and thus break the web. Stationary guide rolls 217
222 guide the web along the desired path. Tumbler 225 also takes
up slack in the web caused by the greater speed of the web through
the haul-in assembly 202 as compared to the speed through the
winding assembly 204.
In a commercially available embodiment of the Gietman et al
device, tumbler 225 has a diameter of at least 5 inches. The
tumbler assembly has a first gap element of at least about 1 inch
between the haul-in assembly and the tumbler 225 and a second gap
element of about 3 inches between the tumbler 225 and the nip
formed by rolls 230, 231 of the winding assembly 204. The overall
length of the gap along the machine direction; between guide rolls
210 and rolls 230, 231, is about 9 inches. Rolls 217-222 are used
to support the web, and to ensure traversal of the web along the
desired path for the length of the gap. Further, the nine inch
2194422
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length of the gap directly affects the overall length of Gietman
et al~s winder 200.
2194422
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8 TMMARY OF THE TNVF' T()N
Some of the objects of the invention are obtained in a first
family of embodiments comprehending apparatus for breaking a web
having a length and a width, the web having spaced lines of
weakness therein and traveling in a given general direction. The
apparatus comprises first and second driven rolls forming a first
nip. The first nip receives and transports the web through the
first nip. The breaker bar assembly comprises at least first and
second breaker bars, and driving apparatus driving the breaker
bars in a downward translational direction. Third and fourth
driven rolls downstream of the breaker bar assembly form a second
nip which receives and transports the web through the second nip.
A controller controls the driving of the driven rolls of the first
and second nips, through the driving apparatus, and directs at
least one breaker bar to engage the web, movement of the breaker
bar in a downward direction causing the web to break.
In some embodiments, the breaker bar assembly comprises a
first rotary element including at least first and second ones of
the breaker bars. The first rotary element is powered by the
driving apparatus to incrementally and intermittently rotate the
breaker bars against the web with sufficient force to cause the
web to break.
The breaker bar assembly can further comprise a second rotary
element including at least third and fourth ones of the breaker
bars. In this embodiment, the web has first and second opposing
edges. The first rotary element is mounted adjacent the first
edge. The second rotary element is mounted adjacent the second
edge. Each breaker bar rotates in a closed path substantially
perpendicular to the direction of travel of the web, the paths
extending across the width of the web.
The driving apparatus preferably comprises a servomotor
powering the first and second-rotary elements.
The breaker bar assembly can further comprise first and
second belts, preferably timing belts, and a gear box, utilized by
2?9442
-5- 29058
the servomotor to rotate the first and second rotary elements.
Any timed drive can be used for first and second belts. Timed
belts are preferred, though timed chains and the like can be used.
Preferably, the breaker bars are disposed in a common plane
extending across the web. The controller drives the first and
second rotary elements in opposite directions, and times rotation
of the rotary elements such that each respective breaker bar on
the first rotary element cooperates with a respective breaker bar
on the second rotary element across the surface of the web such
that the respective breaker bars concurrently engage, and_break,
the web. Cooperating ones of the breaker bars are preferably
substantially aligned with each other when the respective breaker
bars cooperatively engage and break the web. The cooperating .ones
of the breaker bars preferably define equal and opposite angles
with the web.
In preferred embodiments, the breaker bars travel in paths
substantially perpendicular to the direction of travel of the web
at engagement with the web.
In some embodiments, the_ breaker bar assembly comprises a
first belt, supporting at least first and second ones of the
breaker bars. The first belt is mounted on first guide apparatus,
and powered by the driving apparatus to incrementally and
intermittently advance the breaker bars along a first elongate
closed path. The breaker bar assembly can include a second belt,
supporting at least third and fourth ones of the breaker bars.
The second belt is mounted on second guide apparatus and powered
by the driving apparatus to incrementally and intermittently
rotate the third and fourth breaker bars along a second elongate
closed path. The first belt is mounted adjacent the first edge.
The second belt is mounted adjacent the second edge. Each belt
is preferably a timing belt, and each guide apparatus is
preferably a respective timing pulley.
It is preferred that major portions of respective first and
second elongate paths extend in straight lines, substantially
perpendicular to the direction of travel of the web, preferably
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parallel to each other. Preferably, the breaker bars on the first
belt travel in a plane in common with respective breaker bars on
the second belt. In this embodiment, the controller drives the
first and second belts in opposite directions, and times advance
of the breaker bars along the first and second paths such that
respective pairs of breaker bars cooperatively engage and break
the web.
Preferably, the web has spaced lines of weakness extending
thereacross, defining respective bags i.n the web. The apparatus
further can include a sensor which senses each line of weakness in
the web.
In a shingling mode of operation, the controller operates the
breaker bar assembly to break the web in response to each sensing
of a line of weakness by the sensor, each breaking of the web at
each line of weakness making an individual workpiece. In this
shingling mode, third and fourth driven rolls are driven at a
slower line speed than the first and second driven rolls, thereby
shingling or overlapping the workpieces between the nips. Thus,
a leading portion of the remainder of the web, after each breaking
at a line of weakness, is placed on a trailing portion of the next
succeeding downstream workpiece between the first and second nips.
The invention further contemplates driving the respective
breaker bar in a preferably downward translational direction
against the web, each driving of the breaker bar assembly against
the web bringing engagement between the breaker bar assembly and
the web at a single line across the width of the web. The
engagement causes the web to break at a line of weakness between
at least one breaker bar and the first nip.
In some embodiments, the breaker bar assembly comprises at
least first and second breaker bars mounted for traversing first
and second elongate closed paths, a first one of the breaker bars
being driven in a first substantially straight line direction
along a first path segment into stressing engagement with the web
at a first location along the length of the web while a second one
of the breaker bars is driven in a second opposite substantially
CA 02194422 2000-OS-15
straight line direction along a second path segment into
stressing engagement with the web at a second location, namely a
second locus of engagement, displaced from the first location
along the length of the web. The combined stressing engagements
of the first and second breaker bars break the web. Each of the
breaker bars moves in a respective straight line direction
before engagement with the web, during subsequent stressing
engagement with the web, and after the web breaks.
In some embodiments, the straight line path segment in each
direction comprises a distance of at least about 4 inches.
In preferred embodiments, the second path segment is spaced
from the first path segment by a distance of no more than 1.5
inches, preferably between about 0.25 inch and about 1 inch.
The first and second path segments can comprise first and second
portions of a single elongate closed path.
In some embodiments, the breaker bar assembly comprises a
first drive belt mounted on first guide apparatus and disposed
adjacent the first edge of the web. The breaker bar assembly
further can comprise a second drive belt mounted on second guide
apparatus and disposed adjacent the second edge of the web.
Each breaker bar is preferably mounted to both the first and
second drive belts and extends transversely across the web. The
second drive belt and second guide apparatus are preferably
substantially aligned, across the web, with the first drive belt
and first guide apparatus. The driving apparatus drives the
first and second belts in common, advancing the breaker bars
along the respective paths.
In some embodiments where the first drive belt is mounted
on f first guide apparatus adj acent the f first edge of the web and
the second drive belt is mounted on second guide apparatus
adjacent the second edge of the web, first and third upwardly
driven breaker bars are mounted on respective first and second
belts in substantial alignment with each other. Second and
fourth downwardly driven breaker bars are mounted on the
respective first and second drive belts in substantial alignment
with each other, such that the breaker bars on each belt advance
in respective
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upward and downward straight line directions before engaging the
web_
In some embodiments, the gap between the web drive assembly
and the nip subassembly is less than about 3 inches. Preferably,
the gap is between about 1 inch and about 2 inches.
In preferred embodiments, the breaker bars engage the web and
exert a take-up force across the width of the web, taking up slack
in the web, and continuing to take up the slack, before breaking
the web.
IO The invention further contemplates a method of breaking a web
at spaced lines of weakness in the web. The method comprises
advancing the web through a first nip formed by first and second
rolls, drawing the web through a second nip formed by third and
fourth rolls, and through a breaker bar assembly between the first
and second nips, sensing a line of weakness, and driving at least
one of the breaker bars in a downward direction, thus engaging the
web, and breaking the web at the line of weakness. The breaking
of the web forms a separated workpiece having a trailing portion,
and correspondingly forms a_leading portion of the remainder of
the web. The breaker bar assembly comprises at least first and
second breaker bars, and driving apparatus driving the breaker
bars.
In preferred embodiments, the method includes incrementally
and intermittently rotating first and, preferably, second rotary
elements in response to successive signals from the controller, in
closed paths substantially perpendicular to the direction of
travel of the web, and extending across the width of the web.
In some embodiments, the method comprises advancing a first
drive belt, and incrementally and intermittently advancing at
least first and second breaker bars along a first elongate closed
path. At least third and fourth breaker bars on a second drive
belt can be cooperatively incrementally and intermittently
advanced along a second elongate closed path.
In some embodiments, the breaker bars travel in path segments
substantially perpendicular to the direction of travel of the web,
2194422
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and extend across the width of the web, during, and before or
after, or both, engagement with the web.
The invention further comprehends a method of breaking a web
including driving a first one of the breaker bars in a first
substantially straight line direction along a first path segment
into stressing contact with the web at a first location along the
length of the web while driving a second one of the breaker bars
in an opposite substantially straight line direction along a
second path segment into stressing contact with the web at a
second location along the length of the web. The combined
stressing contacts of the breaker bars break the web at the
respective line of weakness.
In some embodiments, the method includes sensing each Line of
weakness, and only when the last of a predetermined number of
lines of weakness has been sensed, breaking the web at the last
line of weakness so sensed, when the last line of weakness is
downstream of the first nip.
In some embodiments, the method includes sensing each line of
weakness, and breaking the web at each line of weakness sensed,
each breaking of the web at a line of weakness making an
individual workpiece comprising a single bag.
2194422
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$ TR DES _ T TON O TF~R 1~RAWTNI"=c
FIGURE 1 shows a representative side view of a first
embodiment of a web handling machine of the invention.
FIGURE 2 shows a representative front view of the breaker bar
assembly taken at 2-2 of FIGURE 1.
FIGURE 3 shows a representative front view of a second
embodiment of the breaker bar assembly.
FIGURE 3A shows a modified version of the embodiment of
FIGURE 3.
FIGURE 4 shows a representative side view of the embodiment
of FIGURE 3, in a web handling machine of the invention.
FIGURE 5 shows a representative enlarged partial side view of
a fragment of a third embodiment of the invention.
FIGURE 6 shows a representative top view of the embodiment of
FIGURE 5.
FIGURE 6A shows a front view of a preferred drive system for
the embodiment of FIGURE 5.
FIGURE 7 shows a top view of a fourth embodiment of the
invention.
FIGURES 8A and 8B show representative top and side views
respectively of a fifthAembodiment of the invention.
The invention is not limited in its application to the
details of construction and the arrangement of the components set
forth in the following description or illustrated in the drawings.
The invention is capable of other embodiments or of being
practiced or carried out in various ways. Also, it is to be
understood that the terminology and phraseology employed herein is
for purpose of description and illustration and should not be
regarded as limiting. Like reference numerals are used to
indicate like components.
CA 02194422 2000-OS-15
-11-
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
FIGURE 1 illustrates a web handling machine 10 including a
dancer assembly 12, a web drive assembly 14, breaking apparatus
illustrated as breaker bar assembly 16 and a winding assembly 18.
The basic overall web handling machine 10 of FIGURE 1, except
for the breaker bar assembly 16, is similar to the machine set
forth in Gietman et al, U.S. Patent 5,362,013. Web 20 has a
width "W" (FIGURES 6 and 7) and a continuous length, and travels
in the direction shown by arrow 21.
Referring again to FIGURE 1, dancer assembly 12 receives web
from a web source (not shown) . In dancer assembly 12, a pair
of rolls 22, 24 assist in controlling the tension on web 20. A
15 position sensor, not shown, associated with dancer roll 24 sends
position signals to electric controller 26 at closely spaced
intervals. Controller 26 uses the position signals to make
ongoing adjustments to the speed at which web 20 is drawn into the
machine 10, thus to maintain dancer roll 24 generally at a mid-
20 point in its range of movement.
Dancer assembly 12 includes a line of weakness sensor 28.
Sensor 28 senses spaced lines of weakness, such as perforations,
in web 20 and provides a signal to electric controller 26 as each
line of weakness is sensed. A variety of sensors are available
for sensing lines of weakness. For example, a pair of electrodes
(not shown) can be provided in cooperative relationship above and
below web 20. A voltage can be applied between the electrodes,
and through the web. The voltage creates an electric arc between
the electrodes when a perforation passes between the electrodes.
Multiple electrodes can be placed at multiple locations across web
20. Sensed signals are sent to electric controller 26 which
controls various elements of web handling machine 10.
Web drive assembly 14 includes first and second rolls 30 and
32, which are urged against each other, thus defining a first nip
34 therebetween. Support belt 44 is stretched about, and
traverses, a first path about rolls 30, 38 and 36. Support belt 46
CA 02194422 2000-OS-15
-12-
is stretched about, and traverses, a second path about rolls
32, 40 and 42. Rolls 38 and 40 are slightly spaced from each
other. Similarly, support belts 44 and 46 are spaced from
each other at rolls 38, 40. Rolls 38, 40 and support belts
44, 46 provide guiding support for the web at rolls 38, 40,
but not a speed-controlling nip as at nip 34.
Support belts 44 and 46 are preferably nylon, or other
suitable polymer or rubber. Support belts 44 and 46 are
preferably full-width conveyor belts, but may comprise
separate ropes or strands disposed in grooves (not shown) in
their respective guide rolls. Support belts 44 and 46 guide
web 20 through web drive assembly 14.
Driving apparatus 48 drives drive belt 50, and thus
drives roll 32 which, in turn, drives roll 30. Driving
apparatus 48 can comprise a servomotor, a standard AC motor or
the like. Electric controller 26 controls the speed of
driving apparatus 48 and thus the speed at which web 20 is
drawn into web drive assembly 14 by rolls 30, 32 at nip 34.
First nip 34 provides a first nip line against which web
20 can be broken. Other structures providing the required nip
can be substituted for the web drive assembly illustrated.
As illustrated in FIGURE 2, breaker bar assembly 16
includes breaker bars 52, mounted on first and second rotary
elements 54A, 54B. Rotary elements 54A, 54B rotate about
respective axis of rotation 55A, 55B which extend along the
length of web 20. While three breaker bars 52 are illustrated
on each rotary element 54 a greater or lesser number of
breaker bars 52 can be utilized.
In breaker bar assembly 16, drive apparatus 56 drives
first drive belt 58 and transfer belt 62. Transfer belt 62
drives second drive belt 60 through guide apparatus 63. Guide
apparatus 63, preferably comprises a pulley or the like.
Drive belt 58 thus drives rotary element 54B in a counter
clockwise direction, while drive belt 60 drives rotary element
54A in a clockwise direction. Accordingly, the respective
rotary elements 54A, 54B drive the respective breaker bars 52
about closed paths, and downwardly into cooperative and
stressing engagement with web 20.
CA 02194422 2000-OS-15
-13-
Driving of the rotary elements 54A and 54B is timed such
that breaker bars from the two rotary elements cooperatively
engage the web at a first locus of engagement, preferably
simultaneously, as illustrated in FIGURE 2 , to break the web at
a respective line of weakness. As each pair of breaker bars
breaks the web at a line of weakness, the next pair of breaker
bars moves, on rotary elements 54A, 54B, into the "ready"
position above the web.
With the web broken, the rotary elements stop rotation
until again signaled by controller 26 to rotate the next pair of
breaker bars into engagement with the web at a second locus of
engagement. Thus, rotary elements 54A and 54B intermittently
rotate in less than full circle increments, to engage the web at
a respective locus of engagement, and break the web each time
they are so signalled by controller 26. Controller 26 can issue
such signal at each sensed line of weakness, or after sensing a
predetermined number of lines of weakness.
The respective closed paths of the breaker bars extend
across the width of the web. Drive apparatus 56 provides
incremental and intermittent driving of belts 58, 60, 62, and
thus the incremental and intermittent driving of breaker bars 52
downwardly against web 20 with web-breaking force, breaking the
web at respective lines of weakness.
While belt 58 advances in a counterclockwise direction,
transfer belt 62 advances in a clockwise direction, as enabled
by a gear box in driving apparatus 56. The gear box can be
omitted, and belts 58 and 62 driven off a common drive pulley.
Transfer belt 62 is then crossed between drive apparatus 56 and
guide apparatus 63, as shown in FIGURE 3, in order to obtain the
proper direction of rotation at guide apparatus 63.
Rotary elements 54A, 54B preferably comprise pulleys or
sprockets with breaker bars 52 mounted from the pulleys or
sprockets. The leading edges of breaker bars 52 engage web 20.
The leading edges typically define arcuate contours as opposed
to sharp edges (not shown). In some embodiments, sharp leading
edge is acceptable, but generally a more arcuate contour is
preferred.
CA 02194422 2000-OS-15
-14-
Typically, the overall cross-sections of breaker bars 52
are round, or other arcuate shapes (not shown). Polygonal
cross-sections, and combination polygonal and arcuate cross-
sections (not shown) are also acceptable. A diameter of 5/8
inch is preferred for breaker bars 52 although other sizes and
shapes can function properly. The general requirement for
breaker bars 52 is a cross-section having sufficient strength to
tension and break web 20. In the preferred embodiments where
the web is broken at lines of weakness displaced from the lines
of contact between the breaker bars 52 and the web, the breaker
bars 52 should be free from sharp edges along all surfaces which
contact the web.
Rotary elements 54A, 54B support respective breaker bars 52
in a common plane extending across web 20. Electric controller
26 drives rotary elements 54A, 54B in opposite directions while
timing rotation of first and second rotary elements 54A, 54B
such that each respective breaker bar 52 on first rotary element
54A is substantially aligned with, and cooperates with, a
respective breaker bar 52 on second rotary element 54B at and
across the top surface of web 20. Thus, the respective two
operative breaker bars 52 (FIGURE 2) at the top of web 20 are
generally oriented parallel to, and transversely across, the web
at first engagement with the web. The operative breaker bars 52
define equal and opposite angles "D" with the web at first
engagement with the web. The angles can be from zero (parallel
to the web), up to about plus or minus 20 degrees with respect
to the web.
Before breaking the web, breaker bars 52 preferably
engage web 20 and apply modest tension, taking up slack without
applying enough force to break the web. Controller 26 senses
the speed of web 20 entering the gap, and the speed of the
workpieces or bags leaving the gap through nip 38, calculates
the amount of slack web material generated at any given point in
time, and the dynamically changing positions of the breaker bars
needed to take up the slack as the slack develops. The
controller accordingly issues commands to the breaker bar drive,
positioning the breaker bars to take up the slack so calculated.
~, 2194422
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In winding assembly 18, driving apparatus 70 drives drive
belt 92, and thus drives roll 66 which in turn drives roll 64.
Driven rolls 64 and 66 define the second nip 68. Web support belt
72 traverses a closed elongate path about guide rolls 78, 80 and
driven roll 66. Web support belt 74 traverses a closed elongate
path about guide roll ?6 and driven roll 64. Web support belts 72
and 74 are similar to web support belts 44 and 46 of web drive
assembly 14.
Web support belt 72 is preferably a flat, full-width conveyor
belt. Web support belt 72 conveys workpieces severed from web 20
toward spindles 84, 86, 88 and 90 for winding. An air horn 96
cooperates with spindle 90 to begin wrapping the workpieces
thereabout.
Electric controller 26 controls the timing and operation of
the elements of web handling machine Z0. While a particular
winding assembly 18 has been disclosed, other winding assemblies
or web processing machines are contemplated as being within the
scope of the invention.
. In FIGURE 1, support belts 44, 46 are shown as cut away
between nip 34 and rolls 38, 40, illustrating a preferred location
where web 20 breaks when stressed by breaker bars 52. A trailing
portion 97 having a trailing edge 97A is shown as a first
workpiece formed by a break in web 20, and a leading portion 98
having a leading edge 98A is shown as a second upstream portion
not yet broken from the web, and which will form the next
succeeding workpiece when broken away from the web at e.g. the
next line of weakness.
The term "bag" used throughout this disclosure is defined as
a section of the web between Lines of weakness. Web 20 preferably
comprises precursors of plastic bags of a selected size.
Preferably, the web, and thus the bags, are made of a plastic
material or the like. However, the bags referred to herein can
comprise other materials, such as sheets or films which are not
bags in the traditional sense. Bags need not have an opening on
any end or side.
2194422
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The term "workpiece" as used herein is a section of web 20
which has been broken or otherwise severed from the continuous
web. Thus a "workpiece" does, in some embodiments of application
of the invention, contain a plurality of "bags."
Each workpiece can comprise a single bag or a plurality of
bags with unbroken lines of weakness between the bags. The
plurality of bags can comprise any number of bags, such as 25, 50
or 100 bags which can be wound on a spindle such as for storage or
for placement into a package.
IO The invention works as follows. Web 20 is drawn into dancer
assembly 22 by the draw at nip 34. Dancer assembly 22 thus
receives web 20 into the machine. In dancer assembly I2, rolls
22, 24 control the tension on web 20. A position sensor (not
shown) associated with dancer roll 24 sends position signals to
electric controller 26 to make ongoing adjustments to the speed at
which web 20 is drawn into the machine 10.
Breaker bars 52 generally do not cut the web. Referring to
FIGURES 1-3, with the web firmly gripped at nip 34, the leading
edge of the web advances. i.nto..nip 68. With the web firmly held,
or anchored, in both nips 34 and 68, breaker bars 52 advance
downwardly against the top surface of the web, applying tensile-
type stress on the web, breaking the web at a line of weakness
between the first and second nips, preferably between first nip 34
and breaker bar assembly I6.
While the drive belts 58, 60 and 62 preferably comprise timed
belts, a variety of other structures can be devised to replace the
drive belts. For example, individual drive motors controlled by
controller 26 can provide the same function.
Line of weakness sensor 28 provides a signal to controller 26
as each line of weakness is sensed. From dancer assembly 12, web
20 follows a path between support belts 44, 46 from nip 34 to
rolls 38, 40.
- Controller 26 controls breaker bar assembly I6, moving
breaker bars 52 downwardly to break web 20 after the sensed line
of weakness passes the first nip 34, and preferably before the
... 2194422
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line of weakness reaches rolls 38, 40. Breaking the web forms a
workpiece having a trailing portion 97, including a trailing edge
97A, and a leading portion 98 of the remainder of the web, having
a leading edge 98A. Breaking of web 20 is repeated at selected
spaced lines of weakness in response to successive signals from
controller 26. In some embodiments, the breaker bars 52 advance
to break the web in response to each line of weakness. In other
embodiments, the breaker bars 52 advance to break the web only
after a predetermined number of lines of weakness have been
sensed.
Second nip 68 continues to draw the broken away workpiece
therethrough, the workpiece being guided by web support belts 72
and 74 toward turret 82. Air horn 96 cooperates with turret 82
and spindles 84, 86, 88 and 90 to wind the leading edge of the
respective bag or workpiece onto the respective spindle. After
the leading portion of the first workpiece or workpieces to be
wound on the spindle has been secured to the spindle (e. g. spindle
84), the turret rotates while the spindle winds the web,
respectively moving the next- spindle (e.g. spindle 90) to the
position shown in FIGURE 1.
In a continuous mode of operation, web 20 is wound,
preferably as a roll of bags connected to each other by the spaced
lines of weakness. Winding proceeds until the winding of trailing
edge 97A of the last bag to be wound on the roll. Electric
controller 26 controls winding assembly 18 so leading edge 98A of
the next group of bags is then wound about the spindle near air
horn 96 and turret 82 again rotates. The selected spindle 84, 86,
88 or 90 having the completely wound roll, rotates, with the
turret, to the next position. A push-off device (not shown)
removes the wound roll of bags from the selected spindle. In this
continuous mode of operation, web 20 is broken at a line of
weakness when a predetermined number of lines of weakness have
been sensed by sensor 28. The predetermined number of lines of
weakness corresponds to a respective preselected number of bags.
In this mode of operation, the preselected number of bags are
21 X4422
-18- 29058
wound onto a first spindle, and then another group of bags,
typically of like number, is wound continuously and sequentially
onto a succeeding spindle.
In the continuous mode of operation, winding assembly 18
preferably operates at substantially the same speed as web drive
assembly 14. This avoids slack in web 20 passing through breaker
bar assembly 16.
In a shingling mode of operation, sensor 28 detects each line
of weakness, and controller 26 controls breaker bar assembly 16 to
break the web into individual workpieces by breaking the web at
each line of weakness. Nip 68 draws the web at a slower speed
than web drive assembly 14, thus creating slack in the web 20 as
the web traverses across gap "G" (illustrated in FIGURES 1 and 5).
Breaker bar assembly 16 takes up the slack created by the speed
differential by bringing respective breaker bars 52 into engaging
contact with the web, using modest force sufficient to take up,
and continue taking up, the accumulating slack, but insufficient
to break the web at the approaching line of weakness. At the
appropriate time, the force is quickly increased sufficiently to
break the web at the respective line of weakness. This process is
repeated at each line of weakness.
As the trailing edge 97A of the leading workpiece moves down
to a lower position below nips 34 and 68, due to the combination
of gravity and the downwardly-directed breaking force, the leading
edge 98A of the remainder of the web 20 feeds past rolls 38, 40,
and over the trailing edge 97A, shingling the leading edge 98A
over trailing portion 97. The amount of the remainder of the web
which overlies trailing portion 97 depends on the difference in
the drive speeds at nips 34 and 68. Increasing the speed
differential increases the amount of web 20 which overlies the
leading workpiece. Winding assembly 18 then winds the shingled
workpieces into a roll on spindle 84, 86, 88, or 90, as earlier
described.
Electric controller 26 can comprise a computer, a
microprocessor or other digital electronic device capable of
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controlling web handling machine 10. Further, electric controller
26 can also comprise an analog electric circuit that receives
inputs from sensor 28, dancer roll 24 and other elements, while
controlling driving apparatus 48 and 70, breaker bar assembly 16,
turret 82 and air horn 96 as well as other elements of web
handling machine 10. Controller 26 can take on other forms. For
example, controller 26 can be a pneumatic or hydraulic controller
using respective pneumatic or hydraulic logic and control devices.
FIGURE 3 illustrates another embodiment of the breaker bar ~~
assembly 16, including first and second drive belts 99, 100 and
breaker bars 52. Drive apparatus 56 can comprise a servomotor, a
standard AC motor or the like. Driving apparatus 56 powers guide
drive apparatus 63 through crossed transfer belt 62. Respective
drive belts 99 and 100 are supported about their respective paths
by respective first and second guide apparatus 102 and 104 in
combination with drive apparatus 56 and drive apparatus 63. Guide
apparatus 102 and 104 typically comprise pulleys, sprockets, or
the like.
Drive belts 99 and 100 preferably comprise timed belts or the
like. The breaker bars 52 are securely mounted to the respective
drive belts and extend outwardly from drive belts 99 and 100 as
shown in FIGURE 3. Breaker bars 52 are powered in a downward
direction to break web 20. By breaking web 20 in a downward
direction, trailing edge 97A of a first workpiece is urged
downward to a position below nips 34 and 68. Leading edge 98A of
the remainder of the web feeds as a straight line extension of
belts 44, 46 from rolls 38, 40, thus feeding over the trailing
edge 97A. This effectively shingles the leading edge 98A over the
trailing portion 97.
Still referring to FIGURE 3, two breaker bars 52 are shown on
each drive belt 99 and 100. A greater number can be utilized.
Breaker bars 52 are carried by drive belt 99 along the entirety of
its closed path via guide apparatus 102 and drive apparatus 56 to _
engage web 20 in a downward translational direction. Drive
apparatus 56 drives the drive belt 99, which preferably is a timed
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belt, along the closed path, including about guide apparatus 102.
Major portions of the elongate path extend in a straight line,
substantially perpendicular to the direction of travel of the web.
Drive belt 100 and respective breaker bars 52 operate essentially
the same way and are in a common plane with breaker bars 52 on
first drive belt 99. The elongates paths of first and second
drive belts 99 and 100 preferably are identical in size and shape.
In operation with respect to FIGURE 3, electric controller 26
drives belts 99 and 100 in opposite directions, illustrated by the
arrows, and thus controls advance of breaker bars 52 along first
and second paths substantially perpendicular to the direction of
travel of the web. Thus, respective breaker bars 52 are
substantially aligned across the top surface of web 20 before
engaging and breaking the web. Breaker bars 52 preferably take up
slack in web 20 by applying an ongoing take-up force, taking up
and sustaining the slack in the web after leading edge 98A is
engaged in nip 68, and before operating to break web 20.
In FIGURE 3A, breaker bars 52 are mounted only on the left
drive belt 100, and extend entirely across the width of web 20 to
right drive belt 99. Right drive belt 99 has receptacles 101
cooperatively spaced with respect to the spacing of bars 52 on
drive belt 100.
Both belts 99, 100 are driven at a common speed, with
cooperative timing such that as each breaker bar traverses about
pulley 104 and extends across web 20 toward belt 99, a receptacle
101 on advancing belt 99 comes into alignment with the breaker bar
and temporarily receives, supports, and preferably locks onto, the
distal end of the breaker bar remote from belt 100. Accordingly,
each breaker bar 52 is permanently mounted to belt 100, and is
temporarily mounted and secured to belt 99 while traversing the
web-breaking downward portion of its closed-loop path. The distal
end of the breaker bar is released from the respective receptacle
101 at the end of the downward portion of the path, thereafter
traversing about drive apparatus 63 and along the upward portion
of the closed-loop path back to pulley 104.
2194422
-21- 29058
Locking onto the breaker bar means restraining the breaker
bar at Least with respect to (e. g. upward or downward) movement
toward or away from the surface of the web which is engaged by the
breaker bar.
Thus, in the FIGURE 3A version of this embodiment, each
breaker bar is permanently mounted to only one of the belts 99,
100. The permanent mount can, of course, be to either such belt,
with receptacles 101 being mounted on the other belt.
As in other embodiments of this invention, driving of breaker
bars is preferably intermittent, and incremental along the
respective closed loop paths, as controlled by controller 26.
FIGURE 4 shows a side view of breaker bar assembly 16 of
FIGURE 3 in web handling machine 10. As with respect to FIGURES
1 and 2, in this embodiment, the length of gap "G" is between
rolls 38, 40 and nip 68 is less than 5 inches, preferably less
than 3 inches, most preferably about one to two inches or less.
Web 20 is unsupported across gap "G."
As the web extends across the gap, gravity urges the
unsupported leading portion 98.of the web downwardly. Stiffness
inherent in the web tends to keep the leading portion 98 moving in
a straight line, generally horizontal direction. The longer the
unsupported length of the web across gap "G," the greater the
gravity effect. Thus, the longer the gap, the greater the
possibility that gravity will overcome the inherent stiffness in
the web, bending the web downwardly such that the web will not
feed properly to nip 68. However, the compact length of breaker
bar assembly 16 of the invention, and the respectively reduced
length of gap "G," reduces the distance the web travels
unsupported, and thus the effect of gravity on the unsupported
web. Because the web crosses the shorter gap "G" in the
invention, rather than the relatively longer gaps of prior art
machines, there is less likelihood of the web mis-feeding due to
web 20 bending downwardly while crossing gap-"G." Hence web
handling machine 10 has greater reliability than prior art web
handling machines.
2194422
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In practice, because of the reduced length of gap "G,"
gravity imposes only nominal practical limitations, at gap "G," on
processes for fabricating webs commonly used to make plastic bags
of e.g. about 0.5 mil to about 2.0 mils thickness of the plastic
web. The shorter gap "G" thus makes the machine 10 more versatile
in that it can handle thinner webs through gap "G."
FIGURE 5 illustrates a side view of a fragment of web
handling machine 10 including a third embodiment of breaker bar
assembly 16 having two breaker bars 52A, 52B engaging web 20 at
spaced locations along the length of the web, to tension and then
break the web. As illustrated in FIGURES 5 and 6, breaker bars 52
are mounted to drive belts 105 and 116 adjacent first and second
edges 120A, 120B, respectively. Drive belt 105 is mounted on
drive apparatus 108 and guide apparatus 110. Guide apparatus 110
and drive apparatus 108 are preferably sprockets, pulleys, or the
like driven by a servomotor, standard AC motor or the like.
Locations 112 and 114 show the positions of respective breaker
bars 52 in a rest position before being driven into engagement
with web 20.
Drive belt 116 is mounted on second drive apparatus 126, and
guide apparatus 118. Drive belts 105 and 116 are mounted in the
web handling machine l0 adjacent the respective edges of the web.
First ends of breaker bars 52 are mounted to drive belt 105.
Second ends of breaker bars 52 are mounted to drive belt 116.
Support belts 44, 46 are omitted between nip 34 and rolls 38,
40, showing where web 20 breaks when engaged and stressed by
breaker bars 52. Drive belt 105 and guide apparatus 110 are
disposed in a first generally planar surface adjacent and
extending generally alongside edge 120A of web 20. Similarly,
drive belt 116 and guide apparatus 118 are disposed in a second
generally planar surface, adjacent and extending generally
alongside edge 120B. See FIGURE 6.
Referring to FIGURES 5-and 6, winding assembly 18 includes
nip subassembly 122, forming nip 68, which securely engages and
grips web 20 after the leading edge of the remainder of the web
- 2194422
-23- 29058
crosses gap "G." Nips 34 and 68 provide nip anchor points against
which breaker bars 52 break the web.
In operation, first breaker bar 52A nearest guide rolls 38
and 40 moves upward in a straight line direction along first path
segment 106 while second breaker bar 52B moves downward in a
straight Line direction along a second path segment 107 into no
more than modestly stressing engagement with web 20, taking up the
slack. The directions of travel along path segments 106 and 107
are shown by arrows 115. This movement of first and second
breaker bars 52 takes up slack in web 20 by simultaneously
extending the web in upward and downward directions. Breaker bars
52 continue to move in the given directions, continuing to take up
the slack, as the web continues to feed across the gap. At the
appropriate time, and as controlled by controller 26, breaker~bars
52 break web 20 by temporarily making a step increase in their
speed of traverse along the path. The break creates a trailing
edge 97A of a first (leading) workpiece, and a leading edge 98A of
a second (trailing and yet to be separated from the web)
workpiece.
After breaking the web, breaker bars 52 move to rest
positions illustrated at e.g. 112, 114 in FIGURE 5, and wait there
until the newly formed leading edge 98A again feeds across the gap
and enters nip 68. The controller then again signals the breaker
bars to take up the slack, and subsequently to break the web as
described above.
As viewed in FIGURE 5, first path segment 106 comprises the
straight line traversed upward by drive belt 105 from the right
edge of driving apparatus 108 to the right edge of guide apparatus
110. Likewise, the second path segment 107 comprises the straight
line traversed downward by drive belt 105 from the left edge of
guide apparatus 110 downward to the left edge of driving apparatus
108. First and second straight line path segments 106 and 107, in
combination with the curved segments about drive-apparatus 108_and
guide apparatus 110, form a single elongate closed path. The
breaker bars 52 move generally along the elongate closed path in
2194422
-24- 29058
a straight line direction, before engaging web 20, while taking up
the slack, while breaking the web, and after web 20 breaks. The
breaker bars, of course, traverse arcuate portions of the path
about drive apparatus 108 and guide apparatus 110.
The respective straight line segments 106, 107 of the first
and second paths are located between respective outside edges of
driving apparatus 108 and guide apparatus 110. Each such straight
line segment is at least about 4 inches in length. Preferably,
each such straight line path segment (106 and 107) is about 8 to
about 10 inches long. Longer path segments are acceptable.
Lateral spacing "S" (FIGURE 5) of first path segment 106 from
second path segment 107 comprises a distance of no more than 1.5
inches, preferably between 0.25 inch and 1 inch. There must, of
course, be sufficient clearance between the path segments to allow
breaker bars 52 to pass one another without interfacing contact
while traversing the elongate closed path.
While FIGURE 5 only shows two breaker bars mounted to drive
belt 105, more are contemplated. Any number of breaker bars 52
can function as long as there. is proper spacing between operative
pairs of bars 52. Namely, spacing between bars 52 must be
sufficient that a following bar does not interfere with feeding
the leading edge 98A of the web across gap "G." In addition, the
spacing from nip 68, across bar 52B to driving apparatus 108, must
be long enough that trailing edge 97A does not become engaged with
driving apparatus 108.
Elements of second guide apparatus 118 preferably correspond
to the elements recited for first guide apparatus 110. Second
drive belt 116 is driven by first drive apparatus 108 via drive
shaft 119. First and second drive belts 105 and 116 are thus
driven at a common speed such that each breaker bar 52 engages the
entire width "W" of the web all at once.
FIGURE 6A illustrates a preferred arrangement of drive shaft
119. As seen therein, drive shaft 119 is driven from line shaft
128 through appropriate coupling (not shown). Spaced pulleys 130,
132 are mounted on and driven by drive shaft 119. Pulleys 134,
2194422
-25- 29058
136 are mounted adjacent respective drive apparatus 108, 126, and
are connected thereto by stub shafts 138. Drive belts 140 connect
pulleys 130, 132 to respective pulleys 134, 136. When line shaft
128 rotates, it causes rotation of shaft 119. Rotation of shaft
119 causes rotation of pulleys 130, 132, drive belts 140, pulleys
134, 136, stub shafts 138, and thus drive apparatus 108 and 126.
FIGURE 6 illustrates guide roll 38 and driven roll 30, but
not web support belt 44 or guide roll 36, in order to show a line
of weakness 121 at a location preferably occupied by each line of
weakness when the web is broken. Line of weakness 121 can
comprise perforations, slits,~weakened portions which have not
been cut through, or the like. The line of weakness 121
preferably extends entirely across web 20 in a direction
transverse to the path travelled by web 20. The line of weakness
121 preferably is at the position shown in FIGURE 6, or even
closer to driven roll 30 when the web is broken by the action of
breaker bars 52.
In the shingling mode of operation, as the breaker bars 52
break web 20, the downstream breaker bar 52 pulls the trailing
edge 97A of trailing portion 97 of the workpiece downward from
nips 34 and 68. Leading edge 98A then extends over trailing edge
97A, overlying trailing portion 97. The trailing edge 97A and the
leading edge 98A are then, together, drawn through second nip 68,
and thence to winding turret 82.
FIGURE 7 shows a top view of another embodiment of the
invention, similar to that in FIGURES 5 and 6. Drive belt 105
supports at Least two breaker bars 52. Drive belt 116 supports at
least two breaker bars 52. Respective breaker bars 52 on drive
belts 105, 116 are in substantial alignment with each other,
across the web, much like the alignment discussed with respect to
FIGURES 2, 3, and 6. The selected breaker bars 52 from each
respective drive belt 105, 116 advance in corresponding upward and
downward straight line directions before, during~and after contact
with web 20. The path segments traveled by the breaker bars 52 on
belts 105 and 116 as the bars advance about driving apparatus 56,
2194422
~....
-26- 29058
guide apparatus 102, drive apparatus 63, and guide apparatus 104,
comprise a pair of elongate closed paths as in FIGURES 5 and 6.
The paths are similar in size and shape, and are adjacent the
respective first and second edges 120A, 120B of web 20. Thus,
breaker bars 52 on the first drive belt are aligned with the
breaker bars on the second drive belt. The embodiment of FIGURE
7 is similar to the embodiment of FIGURES 5 and 6, except for free
ends 123, 124 of breaker bars 52 intermediate the width "W" of web
20.
FIGURES 8A and 8B illustrate a further embodiment of the
breaker bar assembly 16. Referring to FIGURES 8A and 8B in
combination, breaker bar assembly 16 comprises first and second
belt support assemblies 143A and 143B. In belt support assembly
143A, pulleys 142A, 142B, 142C, and 142D define a first closed-
loop rectangular path, traversed by endless belt 144, and defined
in a first containing surface such as plane "P1." In belt support
assembly 143B, respective pulleys 146A, I46B, 146C, and 146D
define a second closed loop rectangular path, traversed by endless
belt 148, and defined in a second containing surface such as plane
"P2" parallel to plane "P1."
Belt support assemblies 143A and 143B are spaced from each
other by...wspace "SP, " and are laterally offset from each other.
Belt support assembly 143B circumscribes the width of web 20.
Belt support assembly 143A is laterally offset from web 20 as well
as being offset, along the length of the web, from belt support
assembly 143B.
Each breaker bar 52 is mounted to both of belts 144 and 148,
for articulation with respect to both belts. As seen in FIGURE
8A, the lengths of bars 52 are disposed parallel to belts 144 and
148 and planes "PI" and "P2," and are positioned between planes
"PI" and "P2." The drawings show two breaker bars 52A, 52B. The
number of breaker bars can be selected according to the needs of
application of a particular web handling machine 10.
FIGURE 8B illustrates the preferred path of travel of the
breaker bars in the breaker bar assembly. As shown, breaker bar
2194422
~.
-27- 29058
52A is disposed adjacent belt support assembly 143A and will next
move in an upward direction, as shown by the arrows 150. The
right end of bar 52A is mounted to belt 144. The left end of bar
52A is mounted to belt 148. Breaker bar 528 is disposed adjacent
belt support assembly 1438, is positioned proximate the top
surface of web 20, and will next move in a downward direction, as
shown by arrows 152. The right end of bar 528 is mounted to belt
144. The left end of bar 528 is mounted to belt 148.
Accordingly, breaker bar 52A extends across a first opening 154A
defined between legs 156A of belts 144, 148 along the right
portions of the respective paths, and bar 528 extends across a
second opening 1548 defined between legs 1568 of belts 144, 148
along the left portions of the respective paths. ,
Controller 26 controls a suitable drive mechanism, not shown,
driving belts 144, 148 in unison, such that belts 144, 148 are
driven at a common speed about their respective closed-loop paths.
FIGURE 8B shows that projections of the closed loop paths defined
by belts 144, 148 overlap at pulleys 142A, 1428, 146C, and 146D.
While such overlap is not necessary, overlap is desirable for
compactness of the assembly 16.
In accord with the structure above described, and starting at
the position of breaker bar 528, driving of belts 144, 148 drives
the breaker bar downwardly in opening 1548, engaging and breaking
web 20. When the breaker bar reaches the bottom of opening 1548,
belts 144, 148 carry the ends of the bar around pulleys 142A and
146A, and move the bar laterally along the bottom segments 158A,
1588 of the paths traversed by belts 144, 148, to opening 154A.
The bar then travels upwardly in opening 154A and is transferred
laterally along top segments 160A, 1608 of the paths traversed by
belts 144, 148, to opening 154A. Back in opening 154A, the
breaker bar again travels downwardly, again breaking the advancing
web at a subsequent line of weakness 121. It will be appreciated
that belt 148 travels around gap "G," and need not pass through
gap ~~ G . ~~
2194422
-28- 29058
Thus, each breaker bar 52 travels a closed-loop path
downwardly in opening 154B, laterally to the right from opening
154B to opening 154A, upwardly in opening 154A, laterally to the
left from opening 154A to opening 154B, and thence downwardly
again in opening 154B. Breaker bar 52B shown, illustrates
downward movement in opening 154B. Breaker bar 52A, shown,
illustrates upward movement in opening 154A. Arrows 162
illustrate the paths of travel of belts 144, 148. Throughout
travel of its closed loop path, each breaker bar maintains its
e.g. parallel orientation with respect to the top surface of web
20.
Primary advantages of the embodiment of FIGURES 8A, 8B are
that,(1) both ends of a respective breaker bar are mounted in the
breaker bar assembly, resulting in the strength and control
inherent in mounting both ends, and (2) the length of the breaker
bar assembly along the length of gap ~~G~~ can be limited to the
space occupied by a single breaker bar, at opening 154B, and need
not provide any length with respect to belt 148 or any other drive
element. This embodiment .thus provides the breaker bar with
strength and control advantages of the embodiment of FIGURE 5, of
securing both ends of the breaker bar while breaking the web, in
combination with the minimal gap lengths of such embodiments as
those shown in FIGURES 1-3.
Where it is desirable to provide an upstream breaker bar 52A
and a downstream breaker bar 52B for cooperating upwardly and
downwardly driven engagement of the web as in FIGURE 5, a pair of
the breaker bar assemblies 16 of FIGURES 8A and 8B can be used.
Namely, a second such breaker bar assembly 16 can be added to the
layout, upstream (with respect to web travel) of the assembly
shown, and with the web extending through the opening 154A wherein
the breaker bars on the second breaker bar assembly travel in an
upward direction to engage the web while the breaker bars on the
first breaker -bar assembly travel.in a downward direction to
engage the web.
-29- 219 4 4 2 2 29058
Throughout the above disclosure, the invention has been
illustrated with a horizontal web 20 and downward movement of
breaker bars 52 into breaking engagement with the web. In the
embodiments of FIGURES 5-7, breaking engagement comprehends a
second, upwardly moving, breaker bar cooperating with the
downwardly-moving breaker bar in breaking the web.
The actual orientation of the web with respect to horizontal
is not limited to that illustrated. For example, the web-breaking
operation can be satisfactorily performed on an upwardly or
downwardly inclined web, including a web advancing vertically
t either up or down) , or on a web running on one edge, such' as
where edge 120B is vertically or angularly above or below edge
120A.
Similarly, breaking the web need not be accompanied by any
downward movement of a breaker bar. Rather, it is important only
that appropriate provision be made to feed the leading edge 98A of
the remainder of the web across the gap to nip 68, and to properly
orient and position the leading portion with respect to trailing
portion 97 when operating in .the shingling mode. Preferably, the
trailing edge is urged generally downwardly or laterally when
broken away from the web. However, upward urgings can also be
tolerated because of the short length of the gap "G," and the
respective limited affect of gravitational forces.
Those skilled in the art will now see that certain
modifications can be made to the apparatus and methods herein
disclosed with respect to the illustrated embodiments, without
departing from the spirit of the instant invention. And while the
invention has been described above with respect to the preferred
embodiments, it will be understood that the invention is adapted
to numerous rearrangements, modifications, and alterations, and
all such arrangements, modifications, and alterations are intended
to be within the scope of the appended claims.
